Chemical Bonding and ?-Aromaticity in Charged Molecular Alloys: [Pd₂As₁₄]^4- and [Au₂Sb₁₄]^4- Clusters.

ABSTRACT: We report a computational study on the structures and bonding of a charged molecular alloy D _2h [Pd₂As₁₄]^4- (1), as well as a model D _2h [Au₂Sb₁₄]^4- (2) cluster. Our effort makes use of an array of quantum chemistry tools: canonical molecular orbital analysis, adaptive natural density partitioning, natural bond orbital analysis, orbital composition analysis, and nucleus independent chemical shift calculations. Both clusters consist of two X₇ (X?=?As, Sb) cages, which are interconnected via a M₂ (M?=?Pd, Au) dumbbell, featuring two distorted square-planar MX₄ units. Excluding the Pd/As or Au/Sb lone-pairs, clusters 1 and 2 are 50- and 44-electron systems, respectively, of which 32 electrons are for two-center two-electron (2c-2e) As-As or Sb-Sb ? bonds and an additional 16 electrons in 1 for 2c-2e Pd-As ? bonds. No covalent Pd-Pd or Au-Au bond is present in the systems. Cluster 1 is shown to possess two globally delocalized ? electrons, whereas 2 has two ? sextets (each associated with an AuSb₄ fragment). Thus, 1 and 2 conform to the (4n?+?2) Hückel rule, for n?=?0 and 1, respectively, rendering them ?-aromaticity.

SUBMITTER: You XR 

PROVIDER: S-EPMC5429782 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature